Prior art reference may be made to U.S. Pat. No. 6,871,462 titled “Composite action system and method” wherein a composite structural system consisting of plates welded to the steel beam and transverse reinforcing members passing through the apertures/perforations in the plates and additional reinforcing members positioned parallel and transverse to the structural members to provide an interlocking composite action between the structural members, reinforcing members, and concrete. The drawback of this system is that it is only suitable for bridge decks or floor slabs, where steel beams are used over which concrete slabs can be cast.
Reference may also be made to www.bi-steel.com wherein a Corus-patented construction material is described. Bi-Steel comprises two steel plates that are permanently connected together to form panels by an array of friction welded transverse bars. These panels are then filled with concrete to create a construction material with outstanding strength. This system has been used in blast resistant construction. The drawback of this system is that it requires welding and minimum spacing between the plates is 200 mm.
A further prior art reference may be made to U.S. Pat. No. 5,426,903 titled “Weld-on dowl for a steel/concrete composite construction”, wherein a Metal weld-on dowel for steel/concrete composite constructions, which has at one end, a weld-on end and at the other end a head for anchoring in the concrete is described. For improving the load-carrying behavior in the case of shear loading, at the weld-on end the shank has a portion with an increased cross-section compared with the shank. The drawback of this system is that it requires welding and there is only discrete connection between the steel plates.
Reference may also be made to U.S. Pat. No. 5,797,235 titled “Double skin composite structures” wherein a connector which provides a joint between two double skin composite panels of a structure and each double skin composite panel comprises a pair of metal icing plates joined together by a plurality of cross-members and filled, at least partially, with a cementitious filler material. The drawback of this system is that the connecting members are welded to the plates and the transfer of shear is at discrete locations.
When a structure is subjected to suddenly applied dynamic loads, an elastic design is seldom possible. Allowing the structure to undergo plastic deformations without losing the integrity is essential to arrive at an economical design. Therefore, ductility and structural integrity are essentially required for structures subjected to suddenly applied dynamic loads. Common construction material concrete, which is normally brittle, is reinforced suitably with steel bars to form laced reinforced concrete (LRC), which enhances the ductility and integrity and which has been successfully used in construction of structures subjected to suddenly applied dynamic loads such as blast. However, LRC construction is complex due to congestion of reinforcement. Also, concrete confined within the reinforcement grill is only effective. Moreover, interpretation of construction drawing needs skilled personnel. Possibility of incorrect interpretation leads to erroneous construction. This difficulty has created interest in developing a simpler structural system, which has properties required for construction of structures resisting suddenly applied dynamic loads. Steel-concrete composite (SCC) system is utilizes the advantages of the both the materials, namely, steel and concrete, efficiently. Bi-steel connector has been used in blast resistant construction, but has the drawback of minimum required spacing between the plates as 200 mm and requires welding. As a consequence to the hitherto known prior art as described herein above, it is clear that there is a need for developing an alternative and simpler structural system which has properties required for resisting suddenly applied dynamic loads, namely, ductility and structural integrity. In this invention, laced composite system is developed, which is simpler and user friendly structural system with improved ductility, which maintains structural integrity even after attaining large deformation, which is essential in resisting suddenly applied dynamic loads, and avoids welding.